How is polycystic ovarian syndrome (PCOS) diagnosed, and what is the role for imaging?
A diagnosis of PCOS is established based on a combination of oligomenorrhea or anovulation, clinical or biochemical evidence of hyperandrogenism, and polycystic ovaries on US. Transvaginal US is the study of choice for evaluation of the ovaries. A diagnosis of polycystic ovaries is supported by imaging when there are 12 or more follicles measuring 2 to 9 mm in diameter, which are often peripherally located, or when the ovarian volume measures greater than 10 mL for at least one of the ovaries. Prominent central ovarian stroma may also be seen. MRI is reserved for cases where US is inconclusive
